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Moon habitat. www.ge.infn.it/geant4/space/remsim. [email protected] Dosimetry for Interplanetary Missions: the Geant4 REMSIM application S. Guatelli 1 , P. Nieminen 2 , M.G. Pia 1. IEEE NSS, October 2004, Rome, Italy. Talk by S. Guatelli.

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Moon

habitat

www.ge.infn.it/geant4/space/remsim

[email protected]

Dosimetry for Interplanetary Missions:the Geant4 REMSIM applicationS. Guatelli1, P. Nieminen2, M.G. Pia1

IEEE NSS, October 2004, Rome, Italy

Talk by S. Guatelli

1. INFN Genova, Italy, 2. European Space Agency, ESTEC, The Netherlands


Vision

A project in the European AURORA programme for the robotic and human exploration of the Solar System

Mars, theMoon and the asteroids as the most likely targets

The radiation hazard to crew is critical to the feasibility of interplanetary manned missions

To protect the crew:

shieldingmust be designed,

the environment must be anticipated and monitored,

a warning system must be put in place

Vision

  • First quantitative evaluation of the effects of space radiation environment on astronauts

    • in vehicle concepts for interplanetary missions

    • in planetary surface habitats

Scope of the Geant4

REMSIM simulation


Outline

Modeling the interplanetary space radiation

Modeling the vehicle concepts and surface habitats

Modeling the physics interactions

Results

First quantitative dosimetry in vehicle and surface habitats

Outline


Software process

The adoption of a rigorous software process guarantees reliability

Essential for mission critical software application

Iterative and incremental approach

First study to evaluate the conceptual possible solution

The Rational Unified Process (RUP) has been adopted as process framework

Sound industrial standard

Equivalent to ISO 15504, level 3 at least

Software process


Strategy

Model of the radiation environment according to current standards

Geant4 based simulation for radiation effects

Dosimetric analysis in a phantom

Vehicle concepts

  • Simplified geometrical configurations

Surface habitats

Essentialcharacteristics for dosimetric

studies kept

Electromagnetic physics

+ hadronic physics

Strategy

  • Physics processes


Space radiation environment

Selected space radiation components: standards

Galactic Cosmic rays

Protons, α particles and heavy ions (C -12, O -16, Si - 28, Fe - 52)

Solar Particle Events

Protons and α particles

Space radiation environment

Worst case assumption for a conservative evaluation

Envelope of CREME96 October 1989 and August 1972 spectra

GCR: p, α, heavy ions

SPE particles: p and α

At 1 AU

At 1 AU

Envelope of CREME96 1977 and CREME86 1975 solar minimum spectra


Vehicle concepts

New and alternative standards vehicle design with respect to hard shell Habitat: inflatable Habitation Module(K.J. Kennedy, NASA JSC, AIAA 2002-6105)

composed by a hard central core and an inflatable exterior shell

transportation module to Mars

waiting on orbit around Mars

transport back to Earth

SIH (Simplified Inflatable Habitat) is a multilayer consisting of:

  • MLI: external thermal protection blanket

    - Betacloth and Mylar

  • Meteoroid and debris protection

    - Nextel (bullet proof material) and open cell foam

  • Structural layer

    - Kevlar

  • Rebundant bladder Polyethylene, polyacrylate, EVOH, kevlar, nomex

Materials and thicknesses of the SIH by: V. Guarnieri, C. Lobascio, P. Parodi, R. Rampini – ALENIA SPAZIO,Torino, Italy

The Geant4 geometry model retains the essential characteristics of the vehicle concept relevant for a dosimetric study

Vehicle concepts


Surface habitats

Example: surface habitat on the Moon standards

Cavity in the Moon soil + covering heap

Surface Habitats

Moon soil

Engineering model by V. Guarnieri, C. Lobascio, P. Parodi, R. Rampini – ALENIA SPAZIO,Torino, Italy

The Geant4 model retains the essential characteristics of the vehicle concept relevant for a dosimetric study


Physics processes

  • Set of Geant4 hadronic models covering the energy range of interest

  • For protons two alternative approaches: Bertini and Binary Cascade in the intermediate energy range

  • Precompound and nuclear deexcitation at low energy

  • Quark Gluon String Models at high energy

Physics processes

  • E.M. Physics

    • Geant4 Low Energy Package for p, α, ions and their secondaries

    • Geant4 Standard Package for positrons

    • Validation of the Geant4 e.m. physics processes with respect to protocol data

    • See:

    • N42-1 Validation of Geant4 Electromagnetic Physics Versus Protocol Data


SIH + no shielding standards

SIH + 10. cm water / polyethylene shielding

SIH + 5. cm water / polyethylene shielding

2.15 and 4. cm thick aluminum structure (conventional engineering design)

vacuum

air

GCR p

GCR p

SIH + 5. cm water / polyethylene

2.15 cm al

4. cm al

GCR particles

SIH + 5 cm water

SIH +10. cm water / polyethylene

SIH +10. cm water

shielding

Phantom: water box

Energy deposit (MeV) with respect to the depth in the phantom (cm)

Multilayer - SIH

Dosimetric analysis of SIH vehicle concept

Configurations

SIH

Geant4 model

The energy deposit is calculated for all the GCR components (p, α, C - 12, O - 16, Si - 28, Fe - 52 ions)


SIH + no shielding standards

Preliminary !

GCR (all ion components)

p

4. cm Al

SIH + 10. cm water

O - 16

C - 12

α

2.15 cm Al

SIH + 5. cm water

e.m. physics

e.m. + hadronic physics – bertini c.

e.m. + hadronic physics – binary c.

Fe - 52

Si - 28

cm

Dosimetric analysis of SIH vehicle concept

Preliminary !

Calculation of the equivalent dose (mSv/day) with respect to the depth in the phantom (cm)

Total equivalent dose in the phantom (mSv/day) with respect to the thickness of the shielding

  • Thicker layer of shielding limit the exposure of the astronaut to the GCR

  • Water and polyethylene have the equivalent shielding behaviour

  • The hadronic contribution to the dose calculation is relevant


Spe shelter model

vacuum standards

Shelter

air

vacuum

SPE energy deposit (MeV) in the phantom with respect to the depth (cm)

SIH + 10 cm water

SPE energy > 300 MeV

SPE p

Phantom

Multilayer (28 layers)

SPE α

GCR and SPE

particles

SIH

SPE shelter model

  • When SPE particles are detected by a warning system, the crew moves into the shelter

Total equivalent dose in the phantom given by GCR:

  • 4.98 mSv/day – e.m. physics

  • 7.83 mSv/day – e.m. + hadronic physics – bertini c.

  • 7.41 mSv/day – e.m. + hadronic physics – binary c.

Preliminary !

Shelter

Geant4 model

Geant4 model


Dosimetry in surface habitats

Worst case (no roof) standards

Add a log on top with variable height x

0.5 m

1.m

vacuum

Moon

soil

1.5 m

2.m

2.5 m

3. m

SPE p – no roof

x

GCR and SPE beam

SPE α– no roof

SPE p – 3.m thick roof

SPE α – 3 m thick roof

e.m. physics

e.m. + hadronic physics – bertini c.

e.m. + hadronic physics – binary c.

Dosimetry in surface habitats

Total equivalent dose (mSv/day) in the phantom with respect to the roof thickness (m)

Preliminary !

Phantom

x = roof thickness - can vary between 0. m and 3. m

Energy deposit (MeV) given by SPE with respect to the depth in the phantom (cm)

SPE with energy > 300 MeV


Conclusions

A standardsfirst quantitative study has been performed in a set of vehicle and surface habitats

Simple geometrical configurations representing the essential features of

vehicle concepts

moon surface habitats

An innovative concept of Inflatable Habitat offers similar radioprotection behaviour as a conventional aluminum structure

with significant engineering advantages

Water and polyethylene have equivalent shielding effects

Water shelter is effective in shielding dangerous SPE

A surface habitat built out of local material looks a possible solution

thickness to be optimised

Preliminary dosimetric analysis to be further refined

Conclusions


Thank you ! standards


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